Once
by gryffindorwriter
Summary: Two months after the events of the Season 7 finale, Matt Casey is having trouble getting Sylvie Brett off his mind. Both of them have changed in the past few months, but the one thing that hasn't changed between them is the unspoken attraction that Matt has been holding off of acting on out of respect to the woman he thinks he might love. A Cassett story set after Season 7.


**A/N**: Long time, no see! I'm back with another fic. This one is going to be about 5-8 chapters long and it starts off being based off of the season finale of Season 7 of Chicago Fire so, if you haven't watched that yet, don't read any further. I don't know about you but I kind of fell in love with Matt and Sylvie when they started hinting about a possible relationship, and I don't think I can wait for Season 8 without any Cassett content, so here I am!

This takes place _after _Season 7 finishes, about two months, and this first chapter is mostly told through flashbacks. There might be occasional flashbacks later on but we get through the bulk of them here. Most of it is taken directly from 7.22 but some of it is based on an idea for this fic I had before I saw the finale. Anyway, I hope you enjoy it and I'm looking forward to continuing to write this and hopefully give you guys some happiness after that finale! Let me know what you think!

* * *

Matt Casey could swear, some days, that all of it was a dream.

It'd been nearly two months since the explosion, the explosion which could have very easily killed every single person inside the factory, and then some. Matt was still counting his lucky stars that he and the whole team made it out of there alive. That the explosion wasn't as bad as they'd all expected it to be. That the worst they'd come away with were a few burns, cuts and scratches.

The mental scars, too, were healing. But slowly.

Everyone was trying to move on from it, and over time it got easier to live with the fact that they'd almost died weighing on their minds. It was easier for some, more difficult for others. Matt fell somewhere in the middle.

He wanted to move on. He wanted for life to go back to the way it was before, but it was hard when he remembered he spent most of the days before it all being confused. Confused about Sylvie, mostly. Back then he was nearly ready to admit having feelings for her. But as time had passed, Matt was certain of those feelings – unable to convince himself otherwise. Those flutters in his chest when he looked at her, when they spoke, when she laughed, couldn't be anything else.

But acting on those feelings now, after everything, didn't sit right.

* * *

_Molly's, the night before the explosion._

_Matt felt an unfamiliar ache in his chest as he looked at Sylvie hugging Kyle from across the room. Hit with the sudden urge to walk over to her and, simultaneously, to leave, Matt stood still, eyes on them. _

_He should have asked her to the dinner before._

_But it was too late now. And that ache in his chest... he didn't like the feeling. Part of him didn't even like dealing with the possibility that the ache meant something real. He wanted to push it down, to ignore it. Because if he acted on it, he knew that his friendship would Sylvie would be ruined because of it. And Sylvie deserved every happiness._

_He tried his best to look and sound normal when he ran into her only a few minutes later. A smile on his face, he greeted her, and she replied. He wasn't even sure what he was saying. But it seemed like the right thing to say, and the words were coming out of his mouth before he could stop them. _

_"It's good to see you back with the Chaplain."_

_"I always liked him... with _you, _I mean."_

_"You guys are right for each other."_

_"You're good together."_

_And then his brain caught up with his mouth, and all he could do was smile at her and walk away before he said something else he'd regret. Word babble. That's all it was. Just word babble. Asking Otis for a drink was both in interest for wanting one and needing to drink to forget the ache growing in his chest as he thought over the words. _

_He drank alone, mostly. Though his eyes kept shifting over to where Sylvie was sitting. He watched Emily leave, he watched her drink more and more, his instincts kicked in, and then Sylvie was looking at him with a furrowed brow as he slid into the seat across from her._

_"How many of those have you had?" He nodded to the empty glass in front of her. _

_"Not enough, I think!" Sylvie laughed, clearly much more than tipsy, and made to stand up. Matt was out of his chair in an instant, making sure she was sitting straight back down in hers. _

_He gave a vague chuckle as she sat back down. "A few too many, _I _think. How about we get you home, yeah?" _

_Sylvie didn't protest at that. She was only drunk because of Kyle. Because of Casey's words that they were good together. Because he was leaving and because she agreed with Casey – they _are _good together. And, she suddenly remembered, she had a shift in the morning._

_"I'll wait with you outside," Matt said after calling Emily, who had only had one drink hours ago, to come and take her home – he would have done it himself if he hadn't been drinking. _

_ As he stood with her outside Molly's, the slightly warm air more than inviting, he kept a close eye on her to make sure she was okay. He'd seen her drunk before, but not _this _drunk. Sylvie clearly noticed._

_"You're doing that thing with me now!"_

_Matt furrowed his eyebrows. "What thing?"_

_"The solemn Matt Casey look that makes all women melt," she hummed. "But I guarantee, I will _not _be melted."_

_His lips twitched up, vaguely remembering another drunk Brett telling him about his apparent look when he was still figuring things out with Naomi. _

_Sylvie kept speaking, though. "I'm stronger than that," she assured him. "Even though every time you give me that look I just wanna grab your face and kiss it. But, like I said, not gonna be melted." _

_The smile on his face disappeared at her words. She was drunk – that was all it was. A drunk Sylvie, too drunk to think straight. There was no truth to her words at all, of course..._

_But then, before Matt had another second to ponder the false words, Sylvie's lips were on his. Kissing him, _actually _kissing him. He'd only barely started to kiss her back when she pulled away, the lights of Emily's car shining around the corner as she pulled to a stop. _

_She stepped away from him with a smile as Emily got out of the car and waved Sylvie over. "I'll see you at work! Have a good night! Don't get too drunk without me!" _

_He watched as Emily's car drove away after that, eyes glued to the disappearing vehicle. But his mind was only on Sylvie and the ache that had returned in his chest. _

* * *

_The morning after, Matt had planned to ask Sylvie about the kiss. To ask her why she'd kissed him and to see if there was anything between the two of them. His heart had been in his throat as he watched Sylvie walking up to the firehouse._

_He hadn't thought anything of Kyle showing up. In all honesty, he'd forgotten all about Kyle and the fact that he and Sylvie were back together, or so he thought. _

_But the second he saw Kyle drop down on one knee, his heart dropped. And suddenly, nothing else in the room mattered. Because the woman who'd kissed him drunkenly last night, the woman that, it dawned upon him, he _liked, _was about to become engaged. The _engaged_ woman who'd kissed him drunkenly last night. The _engaged_ woman that he liked as more than a friend. _

_And everyone else in the room seemed to be more excited about the fact than he was. Deep down, he couldn't help but feel terrible about it, but on the surface, shock was still radiating through his system. And Severide, beside him, was looking at him in some kind of way, like he _knew _what Matt was thinking. But how could he when Matt didn't even know himself?_

_The congratulations in the kitchen later felt forced as he said it. And Sylvie's words after were like a punch straight in the gut as well as a confirmation that she had no memory of the kiss. Two punches to the gut._

_"It's what you said to me, actually. You said that Kyle and I are right for each other and I really thought about that all night. And then he showed up here."_

_And then: what are you supposed to say after the woman you like has just been engaged to another man? _

_"I'm happy for you." It seemed right enough. But it was a lie. A lie through and through. He _wanted _to be happy for her. He really wanted to. But he couldn't find it in himself to mean it._

* * *

As Matt sat down with a bowl of cereal in the dining room of the firehouse, his eyes found Sylvie, sitting on the couch staring at the television. He watched her briefly before he dug into his cereal, eyes pausing on her hand – the hand which no longer contained an engagement ring.

She hadn't explained everything to him. It'd mostly been through Severide, who'd been told about it by Stella. That after the explosion, after Sylvie was released from hospital a few days after, Kyle had been insistent on still moving and setting up a base for his new job. Insistent that he'd be able to take care of her there while she recovered from the trauma of everything. That Sylvie had given him the ring back and told him to go without her.

Back then, Matt was still too caught up in his own mind to really worry about that. But now, as he sat looking at her, it was all he could think about. That he wanted to feel happy for her when she got engaged, but now that she wasn't engaged anymore, the happiness he felt was electric. He remembered how happy she looked on that day, and he hadn't seen that look in her eyes since.

And Matt decided that he wanted to be the one to bring that look back.


End file.
